Abstract
Lead tetraacetate oxidation of 1-(3', 4'-dimethoxy- or 3', 4'-methylenedioxy-benzyl)-6-hydroxy-7-methoxy-2-methyl-1, 2, 3, 4-tetrahydroisoquinoline (1a or 1b) in CH2Cl2 was found to give quantitatively a diastereomeric mixture (1 : 1) of an o-quinol acetate (2a or 2b), treatment of which with Ac2O-conc. H2SO4 at room temperature led to (±)-O-acetyl-predicentrine (5a) or -isodomesticine (5b). Furthermore, hydrolysis of 5a or 5b with 1.7% KOH-MeOH afforded (±)-predicentrine (6a) or (±)-isodomesticine (6b).
